1. Field of the Invention
This invention relates to directional drilling apparatus and more specifically to a configuration of a production shoe and a wireline tool particularly advantageously suited for operation with a directionally drilled or slant drilled borehole.
2. Description of the Prior Art
Cable-suspended well tools, commonly referred to as "wireline tools" are employed in borehole operations for a myriad of purposes. For example, it is not uncommon for parts of the drill string, tubing, packers and other component parts of oil and gas well apparatus used for completing and operating in a borehole to become loose and fall to the bottom of the well, often below the end of the well tubing. When this occurs, it is common practice to lower a wireline "fishing tool" to hook or otherwise attached to the "lost" apparatus so that it may be raised and retrieved. The raised apparatus commonly has projections and irregular shoulders which snag with the bottom or lowermost parts of the well tubing and cause jamming. Upward pulls to hopefully break the jam often cause wireline breakage, breakage of the wireline tool or the apparatus attached by the tool.
Although fishing tools are one type of wireline tool, there are many others, all of which when raised past the lower end of the well tubing are in danger of snagging or sticking.
When the borehole casing is not substantially vertical, and there are many extremely angular boreholes in the field as a result of intentional directional drilling, as well as those slanted because of unintentional slant drilling, then the snagging problems are accentuated. This is because the retracted tool scrapes the internal part of the borehole casing and does not dangle or suspend itself in a centralized fashion. Hence, if there are any projections on the lower side of the slanted borehole, the retracted tool will surely encounter them.
Skillful wireline tool operators by such manipulations as backing off, jiggling and rotating the tool are able to overcome some of the shortcomings just described. But not all sticking problems can be overcome by such skillful tool operation, resulting in losses and down time, which are reduced and virtually eliminated with respect to lower well tubing projections by the present invention. Further, the need for a highly skilled and patient operator is eliminated.
Therefore, it is a feature of the present invention to provide an improved means for reducing the sticking of retracted wireline tools.
It is another feature of the present invention to provided an improved means for centralizing retrieved wireline tools to prevent snagging on the lower end of a well tubing through which the wireline tools are lowered and then raised.
It is still another feature of the present invention to provide a valving means attached to the lower end of a well tubing that allows the pressurizing of the tubing for lowering it, the setting of well packers, the testing of the production tubing and the like, which can then be subsequently sheared free to permit lowering and retrieval of wireline tools therethrough without snagging.